Fiat 1995 Brava, Service Manual

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Bravo ft E n g i n e
Fuel system
10.
S Y S T E M FOR R E C I R C U L A T I N G G A S E S C O M I N G F R O M T H E ENGINE C R A N K C A S E
This system controls the emissions, from the engine crankcase, of breather gases made up of air/petrol
mixtures and burnt gases which escape from the piston seals, in addition to lubricant oil vapours, recir-
culating them to the inlet.
The breather gases, directedd by special walls, rise by the engine oil filler and then pass through the
labyrinth (7), under the tappet cover, where they lose part of the oil which they contain, in the form of
droplets, falling on the camshafts through the pipe (6).
The siphon shape of the pipe (6) prevents the breather gases from escaping and only allows the recircu-
lation of the droplets of oil.
The remaining gases escape from the intake (5) inside of which there is a spark out (4) (to prevent the
phenomenon of combustion due to flame returns from the butterfly casing).
From the intake (5) the breather gases reach the T union (3).
With the butterfly open, the gases flow through the intakes (1) and (2) to be drawn into the manifold.
With the butterfly closed, the vacuum in the inlet manifold draws in the gases through the intake (1)
which contains a PVC restricting valve (8) (Positive Crank Ventilation) which shutters the intake.
The PCV valve can, in effect, be modulated and the quantity of gas which passes through is proportional
to the vacuum in the inlet manifold.
When the butterfly valve is completely open (condition A ) , the vacuum inside the inlet manifold is mini-
mal, the spring (10) is fully extended and the PCV valve allows the maximum flow of breather gases.
Viceversa, with the butterfly completely closed (condition B ) , the vacuum inside the manifold is maxi-
mum, this causes the movement of the piston (9) which shutters the section through which the breather
gases flow inside the PCV valve thereby restricting the intake of the actual gases in the manifold.
A
P4A11FJ01
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